The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

The power of sourdough (LM)

mwilson's picture
mwilson

The power of sourdough (LM)

featuring Renato Bosco. Instagram

DanAyo's picture
DanAyo

Pretty impressive testimony to the power of levain.

Our Crumb's picture
Our Crumb

Thanks for posting this Michael.  Especially because it so dramatically illustrates the Italian lievito practices of which I struggle to understand the purpose.  Physically confining levains with bindings obviously allows CO2 to build up (to dangerous pressure! but not usually) in the packet.  My assumed reasoning about why this is done is that the accumulated CO2 'waste' product negatively feeds back and thereby restricts growth of the bugs that produced it: the yeast(s), or perhaps simply by depriving them of O2.  That would thus leave their unconsumed food available for the non- or less-CO2-producing and O2-dependent members of the levain - the LABs, and other flavor-generating (anaerobic??) bacteria.  This is interesting because it would represent another culture's solution to the challenge of promoting bacterial over yeast growth that rus brot has shared in the Russian CLAS practice.  Granted, that protocol seems to shift the system to rather more acidic bugs than Italian levains would be expected to favor.

So is that the logic behind (and consequence of) Italians' bound levains?  I realize the practice evolved from experience and positive reinforcement from the delicious products it yielded, not because traditional bakers had degrees in microbiology and designed it that way.  But I'm just trying to rationalize why it is done and why it works.

Thanks,

Tom

Yippee's picture
Yippee

I have had the same question/doubt in mind.

Yippee

mwilson's picture
mwilson

The bound method. 

Indeed the intention here is to trap CO2 and create an anaerobic environment. In the English translated book Cresci, Massari says CO2 "fixes" the acidity. I think what is meant here, is that the CO2 contributes to the development of acidity and helps to bring the overall acid toward a desired parameter. As I understand it; This occurs as CO2 is forced to dissolve into the available water which then forms Carbonic acid. With increasing pressure and concentration the pH will decrease faster than it would otherwise. This matters as pH is a growth limiting factor of the LAB found in sourdough starters and therefore the ability to metabolise sugars into acid is impeded. Massari says a bound lievito madre will consume sugar more slowly whereas if unbounded the lievito will consume sugar in half the time.

Other sources of Italian literature on the subject have described how this anaerobic method shifts acid development toward a more lactic fermentation. This is important as lactic acid has a stronger influence on pH and its presence will affect acid balance in the final dough.

Citing Foschino and Galli, 1997, Pagani, Lucisano and Mariotti, 2014 wrote...

"The seed sour (from a previous dough) is left to ferment under controlled conditions, often tightly wrapped in a cloth. This method maintains high CO2 content in the mass, thus lowering the redox potential and enabling heterolactic fermentation to take place"

It is important to remember that this technique was developed in the days before refrigeration was widely available and was found to be a viable solution to delay fermentation while no one was in the bakery. Interestingly during a college lecture in oenology I leant that a very similar method was once used in the production of wine for the same reason. Actively fermenting wine would be transferred into an airtight tank, presumably without headspace and sealed very tightly so that it would become under pressure. The result of this was a retarding of the fermentation.

There has been some previous discussion on TFL about the binding of a natural starter and it appears very few users, if any, other than myself actively employ it. Such is the case that some discussions have perhaps unfairly dismissed this technique, suggesting it to be merely a traditional practice that served no real purpose. I can safely claim this technique does indeed modify fermentation and the practical application works as understood by professional bakers. From small scale bakeries which produce panettone artigianale to large scale commercial production where 1000+ loaves of Panettone are rolled out daily, this method can be found to be an integral part of the processing.

The natural starter used in the formulation of Panettone needs to meet specific technological parameters and the binding method helps to achieve this. While alternative methods do exist all options require extensive knowledge and skill to achieve success. Massari prefers this method and says "it guarantees excellent results".

References:
Pagani, M.A., Lucisano, M. and Mariotti, M., 2014. Italian bakery products. Bakery Products Science and Technology, Secondth edn, pp.685-721.

 

-Michael

mwilson's picture
mwilson

mwilson's picture
mwilson

Large scale production in Dec 1938..

SeasideJess's picture
SeasideJess

I love this. There's something very comforting about watching all those people working together to make delicious bread. 

MTloaf's picture
MTloaf

Interesting technique when the freestanding dough is cinched with the panettone paper. That explains the vertically elongated  crumb in the ones I buy. Some day I hope to attempt the "Mt Everest of bread". Thanks for all the great info on the subject.